1. Field of the Invention
The present invention relates to a map change detection device that detects changes such as changes in houses and buildings on a map. The present invention more specifically relates to a map change detection device, a map change detection method, and a map change detection program that detect changes in houses and buildings etc. on a two-dimensional map using digital surface layer model data obtained from a stereo image.
2. Description of the Related Art
As a method of detecting changes in maps, a method of detecting changes in housing exists where a map is projected onto aerial photographs. Changes in housing are then detected by comparing the buildings on the map and the buildings on the aerial photographs one at a time by visual observation. This approach is, however, extremely expensive because it is necessary to investigate all changes in buildings on the map by visual observation. Detection can be missed because the operation is a manual operation.
Changes in the maps are indicative of changes caused by buildings being knocked down or by new buildings being erected. A building being knocked down refers to a building being removed and becoming a vacant land lot. A building being erected refers to a building being newly added to a vacant land lot.
As a result of this situation, a method of detecting changes in maps using aerial photographs and satellite images etc. was proposed, as disclosed in, for example, Unexamined Japanese Patent Application KOKAI Publication No. 2002-63580 (patent document 1). In Unexamined Japanese Patent Application KOKAI Publication No. 2002-63580, an image matching method is disclosed where two types or more of images taken of the same region using aerial photographs or satellite images are utilized. Images are then automatically searched from images of buildings matching with indefinite forms made from house shapes on the map. When an indefinite form no longer exists, it can be known that the building is no longer there.
In addition, technology that determines changes in buildings from old and new image data or laser data is disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-117245, Unexamined Japanese Patent Application KOKAI Publication No. 2007-3244, and Unexamined Japanese Patent Application KOKAI Publication No. 2007-34808. Moreover, technology is disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-198530 and Unexamined Japanese Patent Application KOKAI Publication No. 2005-234603 where maps and image data are collated and changes are determined by detecting new features.
A method is also disclosed in Unexamined Japanese Patent Application KOKAI Publication No. Hei. 03-167678 where three-dimensional numeric data is obtained from stereo images.